1. Field of the Invention
The present disclosure relates generally to the field of segmental retaining walls and, more specifically, to corner blocks for use in forming a corner of a segmental retaining wall and techniques for manufacturing segmental retaining wall corner blocks.
2. Background Information
Retaining walls are widely used in a variety of landscaping and construction applications. Typically, they are used to maximize or create level areas and also to reduce erosion and slumping. They may also be used in a purely decorative manner. In the past, retaining wall construction was labor intensive and often required the skills of trained tradespeople such as masons and carpenters. More recently, retaining wall construction has become significantly simplified with the introduction of self-aligning, modular, molded blocks of concrete that may be stacked in courses without the use of mortar or extensive training. With these types of retaining wall blocks, it is possible to erect a segmental retaining wall quickly and economically, and the finished product creates the impression and appearance of a conventional block-and-mortar retaining wall.
One feature that allows the foregoing blocks to be so easily and precisely assembled is the interconnection between adjacent courses of blocks. Typically, each retaining wall block has one or more projections and one or more recesses located at oppositely facing surfaces, such as a top surface and a bottom surface, for example. The projections and recesses are complementarily shaped, with the projections protruding beyond the top (or bottom) surface of the block and the recesses extending inwardly from the bottom (or top) surface of the block. In use, the projections of a first block are received within the recesses of a second block to interconnect and position the blocks one atop the other in a predetermined relation. When assembling a retaining wall, such interconnections make it possible to lay successive courses of blocks in an accurate and expedient manner. Moreover, such an assembled retaining wall is able to resist lateral forces exerted by the material being retained and reduce bowing. Blocks having these interconnections are usually the same size and may be assembled in a coplanar arrangement in only a simple, running bond pattern. Application Ser. No. 11/900,434, which is incorporated by reference herein in its entirety, discloses retaining wall blocks in which the projections and recesses are arranged so that adjacent courses are set back or offset a predetermined amount. With this type of retaining wall block, each successive course is offset from the preceding course by the same amount (setback) so that the assembled wall is skewed or sloped at a predetermined angle from the vertical.
When installing a segmental retaining wall, it is often necessary to construct a 90° corner which requires use of corner blocks. In the case of segmental retaining walls in which each successive course is set back a predetermined setback from the preceding course, each successive corner block must also be set back from the preceding corner block. Moreover, the setback of the stacked corner blocks must be the same as that of the retaining wall and furthermore, the setback must be formed on two sides of the corner to match the setback of the two runs of the retaining wall that extend from the corner.
The segmental retaining wall industry has several methods of providing for an interlocking stacked corner using corner blocks, both with and without external connectors. These include:
(1) A raised front lip which engages the bottom front and side of an upper corner block. This block must be made with an external “core puller” which adds time to the manufacturing cycle and therefore is costly to produce.
(2) A lower rear lip which engages the top rear surface of a lower corner block. This block utilizes one of its “full stretcher” blocks that has been manually hand-split to provide the corner piece. This method therefore is costly to produce.
(3) A lower core that engages the inside front and side wall of a lower corner block inside the block cavity. This block is manufactured as a solid unit and therefore is costly to produce.
(4) Other corner blocks are installed utilizing pins or connectors and therefore are costly to produce.